Preface

Introduction

fastBinaryJSON is based on my fastJSON article (http://www.codeproject.com/Articles/159450/fastJSON) and code which is a polymorphic object serializer. The main purpose for fastBinaryJSON is speed in serializing and deserializing data for the use in data transfer and storage to disk. It was created for my upcoming RaptorDB - Document Database engine, for performance.

Features

fastBinaryJSON has the following feature list:

Based on fastJSON code base (very fast, polymorphic)

Supports : HashTables, Dictionary, Generic Lists, Datasets, ...

Typically 2-10% faster on serialize, 17%+ faster on deserialize.

Why?

Why another serializer you may ask, why not just use fastJSON? The answer to this is simple : performance. JSON while a great format has the following problem:

JSON is a text format, so you loose type information on serializing which makes deserializing the data again time consuming.

Why not BSON?

Looking at the specifications on the above site, you feel overwhelmed as it is hard to follow.

You feel that the specs have evolved over time and a lot of the coding parts have been deprecated.

BSON encodes lengths into the stream which inflate the data, this might be fine for the use case the authors envisioned, but for data transfer and storage it just makes things larger than they need to be.

Because of the length prefixes, the encoding of the data object must be done in two passes, once to output the data, and a second time to set the length prefixes.

I initially started off by doing a BSON conversion on fastJSON but it got too complicated, so it was scrapped.

How is data encoded in fastBinaryJSON?

JSON is an extremely simple format, so fastBinaryJSON takes that simplicity and add the needed parts to do binary serialization. fastBinaryJSON follows the same rules as the JSON specification (http://json.org) with the following table showing how data is encoded:

As you can see from the above all the encoding rules are the same as JSON and primitive data types have been given 1 byte tokens for encoding data. So the general format is :

TOKEN, { DATA } : where DATA can be 0or more bytes

Strings can be encoded in 2 ways, as UTF8 or Unicode, where UTF8 is more space efficient and Unicode is faster.

String keys or property names are encoded as a special UTF8 stream which is limited to 255 bytes in length to save space (you should not have a problem with this as most property names are short in length).

Performance tests

To get a sense of the performance differences in fastBinaryJSON against fastJSON the following tests were performed, times are in milliseconds, each test was done on 1000 objects and repeated 5 times, the AVG column is the average of the test excluding the first which is skewed by initialization times:

As you can see in the DIFF column which is [ fastJSON / fastBinaryJSON ] the serializer performs at least 2% faster and the deserializer at least 17% faster, with the greatest difference being with DataSet types which are a lot of rows of data.

Now to do this fastBinaryJSON is using the FormatterServices.GetUninitializedObject(type) in the framework which essentially just allocates a memory region for your type and gives it to you as an object by passing all initializations including the constructor. While this is really fast, it has the unfortunate side effect of ignoring all class initialization like default values for properties etc. so you should be aware of this if you are restoring partial data to an object (if all the data is in json and matches the class structure then you are fine).

To control this you can set the ParametricConstructorOverride to true in the BJSONParameters.

Appendix v1.4.0 - Circular References & Breaking changes

As of this version I fixed a design flaw since the start which was bugging me, namely the removal of the BJSON.Instance singleton. This means you type less to use the library which is always a good thing, the bad thing is that you need to do a find replace in your code.

Also I found a really simple and fast way to support circular reference object structures. So a complex structure like the following will serialize and deserialize properly ( the unit test is CircularReferences()):

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About the Author

Mehdi first started programming when he was 8 on BBC+128k machine in 6512 processor language, after various hardware and software changes he eventually came across .net and c# which he has been using since v1.0.
He is formally educated as a system analyst Industrial engineer, but his programming passion continues.

* Mehdi is the 5th person to get 6 out of 7 Platinums on CodeProject (13th Jan'12)